Optimal microstructures on fatigue properties of friction stir processed NiAl bronze alloy and its resistant fatigue crack growth mechanism

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2020-01, Vol.771, p.138577, Article 138577
• Main Authors: Lv, Yuting, Nie, Bin, Wang, Liqiang, Cui, Hongzhi, Li, Lei, Wang, Rui, Lyu, Fuyan
• Format: Article
• Language: English
• Subjects: Fatigue properties; Friction stir processing; Microstructures; Nickel-aluminum bronze
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2019.138577

Friction stir processing (FSP) is a feasible way to improve mechanical properties of nickel-aluminum bronze (NAB) alloy. However, not all the microstructures obtained by FSP have high fatigue properties. In this paper, various microstructures of FSPed NAB alloy were prepared by different FSP tools, and optimal microstructures on fatigue properties was obtained. The resistant fatigue crack growth mechanism of the microstructures was also systematically studied. The results show that optimal microstructure contains fine equiaxed α grain, lots of micron and nano κ phase and few residual β phase (βˊ phase). The strengthening mechanisms mainly contain grain refinement, second phase strengthening, work-hardening and nanotwin strengthening, and the fine equiaxed α grains and large quantity of micron and nano κ phase make a main contribution to the better fatigue properties. Finally, Zener-Holloman parameter for forming the optimized microstructures was estimated by theoretical calculation.